This invention relates generally to processes for manufacturing semiconductor integrated circuits.
In a number of situations, various materials associated with integrated circuits fabrication may be removed by a process called etching. Etching may involve using chemicals to remove a material from a wafer. Etching may encompass both wet and dry etching and also includes cleaning processes using chemicals to attack materials that are undesirably present on the wafer. Surface conditioning is a process for modifying the top monolayer of a film or substrate (such as converting the surface bonds of silicon from Si—H to Si—OH).
Various etching and cleaning compositions have been formulated to attack etch or clean resistant materials. Many of these approaches are relatively expensive and have only limited efficacy. Selectively removing a particular type of film or residue while leaving underlying or contiguous film(s) intact is a challenge.
For example, the removal of antireflective coatings, photoresist, and sidewall polymers to enable interconnect patterning, is proving to be difficult because of the lack of selectivity of the chemicals used to remove residues. This means that the chemicals used to remove undesirable residues may also attack desired dielectric materials.
Cleaning of residues has typically involved a combination of plasma ash and wet cleans. However, lower dielectric constant films, such as porous carbon doped oxides, are particularly vulnerable to degradation during plasma ash. Thus, with particularly sensitive materials, such as low dielectric constant films, wet cleaning alone is only used to remove the residues. But, of course, using only wet cleaning may prove to have less than ideal efficacy.
Thus, there is a need for better ways to etch materials in semiconductor processes.